Electromechanical short interval timer

ABSTRACT

An electromechanical short interval timer has an actuating dial which can be manually rotated from a rest position to establish a time-elapse period. An electric motor returns the dial to its rest position. A timing circuit delivers electric pulses to drive the motor. A frequency selector switch is connected to or within the timing circuit whereby the pulse frequency can be varied. In this way, the time elapse period which is set by a given amount of dial rotation can be varied in a simplified manner. The dial activates a signal emitter before reaching its rest position, and simultaneously activates a timer circuit to continue returning the dial to its rest position. The dial engages a movable stop at both ends of its 360 degree travel stroke which assumes that the dial travels exactly 360 degrees.

BACKGROUND AND OBJECTS OF THE INVENTION

The invention concerns an electromechanical short interval timer.

Such a timer includes an activating element which can be moved manuallyfrom a rest position and then returned to its rest position by means ofa motor. The motor is controlled by an electronic timekeeping circuit toreturn the activating element, whereupon the latter actuates a switchfor energizing a signal emitter.

Short interval timers of this type have been exhibited at the EuropeanTimepiece and Jewelry Exhibition 1982 (Basel, April, 1982). They exhibitcertain advantages resulting from being driven by means of anelectromechanical transducer actuated by a quartz stabilized timekeepingcircuit (as in the case of conventional quartz analog mechanisms). Thatis, they may be manufactured less expensively than conventional shortinterval timers of the type having mechanical spring mechanisms, whileproviding higher accuracies with respect to the timing period and signalgenerator actuation.

It is an object of the invention to expand the possible applications ofa short interval timer of this type and to further improve itsfunctional reliability.

SUMMARY OF THE INVENTION

This object is attained according to the invention which involves anelectromechanical short interval timer. The timer comprises a housing,an actuating element mounted on the housing for manual movement from arest position, and a control mechanism for returning the actuatingelement to its rest position. The control mechanism includes an electricmotor operably connected to the actuating element, an electric powersource, an electric timekeeping circuit connected to the power sourcefor supplying electronic actuating pulses to the motor, and a manuallyadjustable mechanism for varying the pulse frequency supplied to themotor. A signal emitter is activated in response to the actuatingelement reaching a predetermined position of its return movement.

Merely by changing the motor pulse frequency, the short interval timerrange may be varied without the need for any interference with thefunctioning of the movement and the dial train or the signal contactoutput actuated therefrom.

In conventional mechanical short interval timers, switching betweendifferent ranges is not feasible in practice, because it would involve agear switching of the gear train coupling the movement with the dialmechanism. However, such switchable gears are expensive, relativelyprone to failure and not suitable for small (household) short intervaltimers in view of their large size.

In contrast, the solution according to the invention enables the dialtrain to be driven by a short interval transducer actuator, as in modernquartz timepiece movements, by means of a stepping motor. It receivesits step switching pulse recurrence frequency from a timekeepingcircuit. The latter consists preferably of a quartz stabilizedoscillator circuit, the output frequency of which is reduced to themotor control frequency by means of a frequency divider. This pulserecurrence frequency may thus be switched in a very simple manner,thereby varying the reset movement velocity of the actuating element,i.e., switching the range of the short interval timer. For this purpose,either the output frequency of the frequency divider is modified (bymeans of different taps or by the insertion of further frequencytransformers) or the input frequency in the frequency divider (byfrequency transformers behind the oscillator or by affecting thetimekeeping circuit itself) is altered. These simple switching modesprovide structurally inexpensive but userfriendly switching measureswith respect to the display of ranges in the short interval scale,without requiring special instructions for certain complex and notreadily comprehended conversions as a function of the range set at themoment. In particular, the range data may be arranged on a rangesupport, which simultaneously also carries the contact springs for rangeswitching (i.e., for the modification of the motor pulse recurrencefrequency) and displays the prevailing range (possibly includingintermediate range data) in the plane of the short interval scale oreven within this scale.

A further disadvantage of short interval timers of this type is thelayout effort required for electromechanical (ohmic) contacts in theactuation of the electromechanical transducer and the electroacousticalsignal emitter, while such contacts offer only a low operatingassurance. For contacting, switching contacts are moving over contactbars provided on an insulating plate, with this arrangement beingsusceptible to interference by soiling and to wear; and differentcontacting ranges are laid out in order to initially actuate theacoustic signal emission shortly prior to the return of the indicatordial into its rest position and then, to effect a second contact afterpassing over this contact range to terminate the actuation of the motorby means of a corresponding actuation of the electronic circuit.

However, this ending of the motor actuation is uncertain, because as theresult of mechanical shock or other contacting uncertainties, theactuation of the motor may be reactivated, leading to an undesirableload on the built-in battery power source, whereby the operating rangeof such an electromechanically driven short interval timer may besignificantly shortened. A further disadvantage of these known shortinterval timers is that a certain minimum sector of the circular timescale is not available for time setting, as this remaining space isfunctionally required for the layout of the scale onset and scale endstop, and for the further progress of the indicator toggle from thesignal emitting position to the motor stop position. In this connection,it is a further disadvantage, that in the case of a new time setting,i.e., rotation from the motor stop position and thus from the restposition, the contact segment for signal emission is again passed over,which in practice, may result in irritation and in any case leads to anundesirable, additional drain on the battery.

According to a further development of the solution according to theinvention, claimed as particularly appropriate, the duration of thesignal emission is no longer determined by a residual angle of rotationof the actuating element, realized for example in the form of anindicator dial to its rest position; rather, practically upon theattainment of the rest position, a timing circuit provided within theintegrated circuit for the actuation of the motor is started, saidtiming circuit being dimensioned for a definite duration of the signalemission. In this manner, the onset of the signal emission may be placedclosely adjacent to the zero point of the scale, i.e., the rest positionof the actuating element, thereby increasing the accuracy in time of theonset of the mission of the signal with respect to the duration of thepreset short interval time range, which especiall with short timesettings has a favorable effect on operating accuracy.

Contacting in this arrangement is conveniently effected by means of abent contact spring, which is protruding into the path of rotation of adriver element revolving with the actuating element and easily adjustedin view of its configuration, so that it abuts shortly prior to reachingthe rest position against a counter contact and triggers the emission ofa singal, which is limited in time by the circuit. This signal emissioncircuit is appropriately designed so that a new signal may be actuatedonly when the time period of the signal already actuated has beencompleted and in any case, the contact has been reopened. In thismanner, undesirable energy consuming signal emissions triggered bycontacting uncertainties are practically eliminated.

A further increase in operating safety results from an improvement incontacting consisting of that the motor remains actuated after a certainresidual period of time, thereby increasing the contact pressure of thebent spring against the counter contact and eliminating contactinguncertainties due to deposits of dirt or external mechanical effects.The actuating element, i.e., the indicator dial is moved during thisadditional actuating phase in a rest position against a mechanical stop,against which it is pressured by means of a frictional rotatingconnection with the gear train driven by the motor; a definite terminalposition is thus assured.

The two time periods, i.e., for the duration of the signal emission andthe duration of the trailing actuation of the motor, are initiatedconveniently by means of the same bent contacting spring. This not onlyreduces the equipment volume compared to the provision of separatecontacts, but also assures the definite onset of the signal emissionshortly perior to the passage of the manually set time range, assimultaneously the trailing run of the motor for the pressuring of thecontact is actuated.

To reduce costs, the trialing actuation of the motor within theintegrated electronic circuit for the timekeeping actuation of the motorand for the determination of the duration of signal emission, may bechosen to equal in length the duration of the signal, i.e., the sametime circuit is used to control the duration of the signal emission andthe trailing run of the motor.

In order to be able to utilize a full circular arc for the times scaleprovided for short interval setting of maximum one hour, according to anadvantageous further development of the invention, a pivoting wedge isprovided as a pivoting locator, which in case of a complete "winding" ofthe actuating element (in the sense of setting a maximum time period),may be deflected in one direction to a stop fixedly mounted on thehousing and upon the return of the actuating element, into its restposition against an opposing stop on the housing.

This pivoting wedge for the variable stop for the actuating element isarticulated advantageously under the actuating disk in the front part ofthe housing, where it cooperates with an activating rib provided underthe actuating element. As by virtue of this variable stop for maximumtime setting and for the definition of the rest position of theactuating element, the circular time scale extends over a full circle,i.e., 360 degrees, for the drive gear connection between the motor andthe actuating element in a cost reducing manner the standard gear trainof a clock movement, from the rotor of the stepping motor to the minutewheel, may be used, whereby the separate manufacturing effort for theproduction and storage of a special gear train (i.e., for driving aminute disk with a rotating angle of less than 360 degrees in one hour)is eliminated.

THE DRAWING

Additional alternatives and further developments, together with furthercharacteristics and advantages of the invention will become apparentfrom the description hereinbelow of the preferred examples of embodimentshown in the drawing with restriction to the essential, at anapproximately true scale, strongly reduced. In the drawing:

FIG. 1 shows a short interval timer in front view, with the front partof the housing removed, and with the actuating element shown in phantom;

FIG. 2 depicts a longitudinal sectional view taken along line II-II ofFIG. 1;

FIG. 3 depicts a detailed, fragmentary longitudinal view taken alongline III-III in FIG. 1;

FIG. 4 is a longitudinal sectional view taken along line IV-IV in FIG.1;

FIG. 5 depicts an electrical control circuit diagram for the timer;

FIG. 6 is a block circuit diagram of an electromechanical short intervaltimer with electric range switching;

FIG. 7 depicts a modified circuit having range switching;

FIG. 8 is another modified circuit having range switching;

FIG. 9 is a front view of a short interval timer with a range switchinghandle annularly surrounding the actuating element;

FIG. 10 is an axial section of a portion of the short interval in FIG.9;

FIG. 11 is a front view of a modified short interval timer wherein therange switching handle is arranged centrally and is surrounded by theactuating element;

FIG. 12 is an axial section of the short interval timer of FIG. 11, witha range switching handle rotatable concentrically with the actuatingelement;

FIG. 13 is a front view of another modified short interval timer,similar to that of FIG. 11, but wherein the actuating has a rib;

FIG. 14 is an axial section through a portion of the short intervaltimer according to FIG. 13; and

FIGS. 15a-15d are schematic representations of the mode of operation ofa range setting handle of the timer according to FIG. 14.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

In a preferred short interval timer according to the invention (FIG. 1),the possibilities of range setting are not shown, in order to initiallyexplain the functioning and a preferred configuration of the fundamentalmechanism. The electromechanical short interval timer has an actuatingelement 1 in the form of a rotating disk 3, set and inserted in themanner of a plate in the front part of the housing (FIG. 2). As shown inFIG. 1, a raised rib 4 forms a rotating handle for the disk and extendsdiametrically across the disk 3. The rib 4 also serves as an indicatorpivotable along a time scale 5. A dial train gear works 6 is connectedto the minute wheel 7 and is rotated by means of a magneticallypositioned rotor 8 of an electromechanical transducer in the form of astepping motor 9. The disk 3 and its rib 4 is rotated in response torotation of the minute wheel 7 through a frictional connection 10. Onthe other hand, the indicator rib 4 may be set manually to an arbitrarytime value of the scale 5 from its rest position 11 (corresponding tothe zero value on the time scale 5) by rotating the disk 3 relative tothe wheel 7 (i.e., the friction connection slips). This avoids the geartrain 6 taking part in the movement and producing actuation of the motorcircuit 12. It may also be assured by these means that the motor 9 isnot blocked mechanically when the rib 4 is already in its rest position.

Following rotation of the rib 4 from the rest position, contacts 20, 23of a switch are opened. Hence, the gear train 6 is driven by theelectronic switching motor circuit 12 via the rotor 8 in such adirection that the disk 3 is moved back in the direction of its restposition 11, due to the frictional connection 10. The electronic circuit12, produced by a conventional integrating technique, contains atimekeeping circuit, known as an electronic clock drive circuit with aquartz stabilized, timekeeping oscillating circuit. The rotating disk 3is coupled in rotation by means of the frictional connection 10, withthe minute wheel 7. The latter is driven by drive portion 15' of a thirdwheel 15, which in turn, is connected for rotation with a second wheel13 by means of a second drive portion 14. An intermediate wheel driveportion 18 of an intermediate wheel 17 connects the second wheel 13 witha drive portion 16 of the rotor 8.

Upon or shortly before the rib 4 reaches the rest position 11, anelectroacoustic transducer 19, preferably in the form of a piezo summersignal emitter is temporarily actuated, as explained hereinbelow. Theduration of this signal emission is not controlled directly or evenindirectly by the remaining return movement of the indicator rib 4 intoits rest position 11. Rather, within the integral electronic circuit 12,a time circuit is developed, preferably derived from the frequencydivider circuit to reduce the timekeeping oscillating frequency to thestep motor actuating frequency. The time circuit causes theelectroacoustic transducer 19 to be actuated for a predetermined timeperiod. Following this period of time, the transducer may be reactuatedonly when the timer circuit is again actuated in accordance with a timesetting. This assures that the duration of the signal emission occursindependently of potential contact uncertainties, and tolerance inducedtrailing run fluctuations of the indicator run 4 in its rest position11. Accordingly, an optimum duration with respect to battery load andsignal effect, is always assured.

Preferably, the signal emission is actuated by means of a spiral spring20, which is urged against a pinshaped counter contact 23 by a driverelement 21 pivotable by the rotating disk 3 and thus moving with theindicator rib 4 shortly prior to reaching the rib rest position 11.Contact between members 20, 23, closes a circuit for the starting of thetime circuit for the signal emission. Disposed on the spiral spring 20,in order to achieve a firm contacting, an angled tab 24 is providedwhich is formed by two blades oriented transversely to and pressedagainst each other. To effect a contacting, the tab 24 is pressedagainst an edge of the counter contact 23 which has a prismaticcross-section (as seen in FIG. 1) with respect to the upwardly deflectedspiral spring 20.

In order to assure this electromechanical (ohmic) contacting even in thecase of potential deposits in the area of the contact surface andindependently of possible mechanical shocks, the motor 9 temporarilycontinues to run even after the onset of the signal emission, so thatthe spiral contact spring 20 with its contact tab 24 is pressed evenmore firmly against the counter contact 23, by means of the gear drive 6and the frictional connection 10. This is achieved in that thecontacting of members 20, 20 to initiate the signal emission also causesa time circuit to be triggered within the integrated circuit 12, whichdetermines the temporary trailing (continuing) run of the motor 9.

Preferably, only a sinle ohmic contact, comprising the spiral spring 20and the counter contact 23 (for the actuation of the signal emission andfor the onset of the trailing run of the motor) is provided. Also, thesame time circuit is used for the limitation in time of the signalemission and for the trailing run of the motor. Following the expirationof the period of time provided for in this time circuit, the actuationof the motor 9 and the electroacoustic transducer 10, is terminated. Theconsumption of power of the circuit 12 from a battery 25 serving as thesource of energy is thus reduced to the minimum determined by the powerconsumption of the oscillator and the frequency divider and is less thanthe spontaneous discharge of a conventional battery 25. The capacity ofa standard round cell R1 thus is sufficient for more than 10,000 runsand signal emissions of the short interval emitter. In the usualapplication of such short interval timers as used in the kitchens ofhouseholds, the need to replace batteries will be extremely rare.

To contain the circuit 12 cast in the usual manner into a DIP housing26, a printed circuit board 27 is provided which is laminated to formprinted strip conductors. The resulting electronic module 28, which maybe preassembled and functionally pretested, is also equipped with anoscillation synchronizing quartz 29, a frequency equalizing capacitor30, a discrete power transistor 31, and the electroacoustic transducer19 actuated by it, and the spiral spring 20, together with the countercontact 23. This electronic module 28 further has soldering terminals 32and 34 for the connection of a motor coil 33 and connecting lines 35.The latter lead to battery contacts 36 fastened to the front walls of abattery chamber 38 molded into the rear part 37 of the housing, such asthose described for example in DE-GM No. 80 24 739, the disclosure ofwhich is incorporated by reference herein.

The motor 9 for the time proportional drive of the gear train 6 for thereturn of the indicator toggle 4 into its rest position 11 may have theconfiguration described in DE-OS No. 31 49 995 (corresponding to U.S.application Ser. No. 06/450,274), the disclosure of which isincorporated by reference herein. However, a greater holding strength atlower production costs is provided under certain circumstances by asingle piece, U-shaped stator plate 39 which is described in detail inDE-GM No. 81 36 794 (corresponding to U.S. application Ser. No.06/448,055), the disclosure of which is incorporated by referenceherein.

The gear train from the motor 9 to the indicator rib 4, includes bearingpins 40 pressed into the housing rear part 37 to receive and rotatablysupport the rotor 8, the intermediate wheel 17 and a hub 41. On thelatter is formed the frictional connection 10 for the minute wheel, aswell as the drive element 21 for the contacting deflection of the spiralspring 20, the element 21 being molded onto a projecting holding arm 42.The second wheel 13 with its drive portion 14 is connected for rotationwith a shaft 43, which is held rotatingly in a sleeve 44 molded in therear part 37 of the housing. For the bearing support of the third wheel15 in the rear part 37 of the housing, a journal 45 is provided as theshaft end of an over-mounted bearing, overlapped by a hub bore 46 of thethird wheel 15, as seen in the sectional view of FIG. 2.

It is further seen in the sectional views according to FIGS. 2 and 4,that hollow columns 47 are molded into the front part 2 of the housing.The columns 47 receive the ends of the bearing pins 40 and shaft 43facing away from the rear part 37 of the housing. The lengths of thecolumns 47 are such as to axially immobilize the corresponding gears ofthe gear train 6, while maintaining the clearance necessary for easyrotary movement. In this sense, a hollow column 48 is associated withthe third wheel, which column 48 is recessed for accommodating a drivingengagement of the third wheel 15 with the minute wheel 7 and radiallysupports a hub 49 of the third wheel opposite this engagement (FIG. 2).

In the area of the sound radiating surface of the electroacoustictransducer 19, the front part 2 of the housing has a sound outletorifice 50. The orifice 50 is located behind a plate-shaped rim 51 ofthe rotating disk 3 so as to be covered to the outside by the rim 51 isopening as a sound outlet orifice under the rim.

The hub 41 has a shaft end 54 which projects into a center orifice 52 ina depressed center part 53 of the front part 2 of the housing. For therotating support of the rotating disk 3, the shaft end 54 has at leastone axial parallel prismatic surface 55. After the joining of the frontpart 2 of the housing to the rear part 37 by means of bolts 56, the disk3 may be frictionally pushed onto the shaft 54 axially from the outside.

In order to be able to use a standard gear train 6 for the returnmovement of the indicator rib 4 into the rest position (i.e., a geartrain 6 used in normal clock movement with a maximum running time of 60minutes for a rotation of the indicator rib 4), it is necessary that therib 4 and thus the disk 3 (frictionally joined to the minute wheel 7)execute an angle of rotation of 360 degrees during the return motion of60 minutes. However, such a rotating angle over a complete circle is notavailable initially, since a segment of the circular path must bereserved to form a stop, against which (independently of a potentialtemporary further drive from the circuit 12 and after the actuation ofthe electroacoustic signal emission) the actuating element 1 abuts toattain its defined rest position 11 and be supported thereat.

To be able to use a standard and thus inexpensively available clockmovement 6, in spite of these restrictions, i.e., to obtain a returnangle of the disk 3 of exactly 360 degrees after one hour, a stop 57 isprovided which is variable with respect to the return movement forarresting the disk 3 in its rest position. This variable stop 57 (FIGS.1 and 3) is in the form of a pivoting wedge 58, held by a pivot journal59 in the radial direction. The journal 59 is molded at the end of aholding arm 60 and extends parallel to the gear axles. This holding arm60 is arranged as a radial extension on an angularly defined peripheraledge area of a plate-like drawn bottom area 61 of a center area range 53of the housing front part 2. A bottom rim 62 of the front part 2 isrecessed for the passage of the pivoting wedge 58 and to form two stops63A, 63B. An actuating boss 64, extending radially under the plate rim51 of the disk 3 abuts laterally against the free end of the pivotingwedge 58 and pivots the latter against the free end of the pivotingwedge 58 and pivots the latter against one stop 63A upon the setting ofthe indicator rib 4 to the maximum time period in one pivotingdirection. After the passing of such period, during the movement of thedisk 3 into the rest position 11, the rib 64 pivots the wedge 58 againstthe opposite stop 63B.

This assures that with a circular time scale 5, a short time interval of360 degrees corresponding to one hour, but no more, may be set. Afterthe passing of this short time interval, even with the temporarilycontinuing trailing actuation of the motor, the return motion of theindicator rib 4 is arrested in the definite rest position 11 with amaximum pressure of the spiral contact spring 20 against its countercontact 23, in a defined manner which is uniform for all operations ofthe timer.

FIG. 6 shows a schematic block diagram of an electromechanical shortinterval timer 81 of the above-described type. The stepping motor 9 andthe transducer 19 are actuated from an electronic circuit 12 with a highfrequency oscillating timekeeping circuit 82 and a frequency divider 83following it in sequence, which are driven by a battery 25.

By means of a range switch 84 (i.e., a frequency selector switchoperating under known principles), the pulse frequency recurrence foractuating the motor 9 from the timekeeping circuit 82 of the switchingcircuit 12 may be selected (FIGS. 7, 8). This determines how many stepsthe motor 9 executes per unit time and how rapidly therefore theactuating element 1 is returned into its signal emitting and restposition 11. To the period of time to which a certain position on thescale 5 (or the entire circumference of the scale) corresponds may thusbe set by means of the range switch 84, through the instantaneous motorpulse frequency recurrence from the circuit 12.

Preferably, the conditions provided by the motor pulse frequencyrecurrences that may be set individually by means of the range switch84, are such that simple conversion factors for the scale 5 or obviousoverall ranges of the scale are obtained. This is the case, for example,when the entire scale, depending on the position of the range switch 84includes 6 minutes, 60 minutes, or 6 hours. If particularly short timeintervals to the signal emission are of interest, the range switch 84 isset to a motor pulse frequency recurrence, which returns the actuatingelement 1 from the terminal position of the scale within six minutes toits signaling and rest position. Correspondingly, a motor pulsefrequency recurrence is set by means of the range switch 84 for the stepmotor 9, which returns the actuating element 1 over the entire scaleafter six hours only, if the emission of the signal is to take placeafter a very long time interval. The signal emission time period of theshort interval timer 81 may thus be varied in arbitrary steps andoptional orders of magnitude simply by affecting the motor pulsefrequency recurrence and without any functionally critical andstructurally expensive intervention in the gear connection between thestep motor 9 and the actuating element 1.

For these switchable settings of different motor pulse frequencyrecurrences according to FIG. 2, outlets 85 may be provided at thefrequency divider 83, or by means of frequency converter circuits, suchas counters or stable trigger circuits, respectively, whereby means ofthe range switch 84', the pulse frequency recurrence required for eachrange to actuate the step motor 9, may be taken off.

Eventually, however, it is less expensive with respect to circuitry toactuate the step motor 9 according to FIG. 8 (as in conventionalelectronic clock movements) always unaffected from the last stage of thefrequency divider 83 and to effect the variation of the motor pulsefrequency divider 83. For this purpose, the pulse recurrence supplied bythe timekeeping circuit 82 may be stepped down or stepped up, in orderto correspondingly reduce or increase the output frequency of thefrequency divider 83; or the timekeeping circuit 82, preferablycomprising a quartz stabilized oscillator, is stepped down or stepped updirectly by means of the range switch 84" by varying the timedetermining circuit components. In case of a configuration according toFIG. 8, which in its effect is equal to the configuration of FIG. 7,therefore the pulse frequency recurrence whereby the step motor 9 is tobe actuated, may be set by the range switch 84; i.e., how rapidly theactuating element 1 of the short interval timer 81 is to be moved backand to what period of time therefore the division of the scale 5 of theshort interval timer is corresponding at a given instant.

This electrical switching of the actuation of the step motor 9 iseffected by a contact spring 86 which engages the printed circuit 27,the latter carrying in particular the electronic circuit layout 12, aplurality of ohmic contacts connected with the pulse outlets 85 and thetimekeeping circuit 82. The spring 86 is connected for movement with arange switch handle 87, to determine the motor pulse frequencyrecurrence by means of the instantaneous position of the range switch 84and thus the overall range of the scale or the instantaneous scaledivision time period. The contact spring 86 may comprise a spiral springwhich is urged in the prevailing switch setting against the associatedcontact on the printed circuit 27. Alternatively, in the interest offavorable contact cleaning conditions, the spring 86 may be shaped as awiper-spring, to be displaced from one switch setting to the other overthe contacts (and the printed circuit 27 located therebetween).

In any case, the part of the printed circuit 27 carrying the contactsfor the switching contact spring 86 extends appropriately along an outersurface of the compact movement configuration of the short intervaltimer 84. Thus, a standardized movement configuration may be equippedwith different setting handles for the actuating element 1 and/or therange switch 84, if only the position of the contact spring 86 iscoordinated with the counter contacts on the printed circuit 27, withoutthe need for an individual intervention for the switching of the motorfrequency. Depending on the configuration and the installation of therange switch handle 87, it is especially appropriate (see the structuralexamples hereinafter described) to equip the printed circuit 27 withcontacts for the range switch 84 in a border area on the surface orclose to the center area on the bottom side of the compact movement 95.

The electromechanical short interval timer 81 outlined in a top view inFIG. 9 has a variable actuating element 1 comprising a rotating disk 3with an indicator rib 4. Also provided is a time scale 5 extending overa full circle. In the scale plate 88, however, at least in the restposition 11 of the indicator, and preferably also at 25%, 50% and 75% ofthe overall range, a sight window 89 is provided, through which isvisible the numerical value of the range which can be set, in this case12 minutes (and in the further sight windows 89 the correspondingintermediate value of the range). The differentially adjustable ranges(in this case the numerical range data for 12 minutes, 120 minutes, and12 hours) are located as the range data 90 on the range carrier 91,extending annularly under the sight windows 89 in the scale 5 andfixedly connection in motion with the contact spring 86 (FIG. 10) andthus with the range switch handle 87. The latter is supported rotatinglyin the form of a knurled switching ring 92 concentrically outside thescale 5 and is connected with the range carrier 91 and the switchingcontact spring 86 (FIG. 10). The spring 86 is movable within a bottomtunnel 93 between the scale 5 and the printed circuit 27, the latterbeing disposed on the cover surface 94 of the short interval timermovement 95.

An embodiment according to FIG. 11 involves an electromechanical shortinterval timer 81A with a scale extending over a full circle and anactuating element arranged in a concentrically rotatable manner withrespect to the scale 5A. In the interest of accurate settings, in viewof the longer curve segments between the divisions of the scale 5A, thescale 5A here is located, with its divisional marks, on the outer edgeof the front part of the housing. The actuating element 1A is in theform of an annular ringshaped disk adapted for gripping, in the centerof which is arranged a diaphragm 96A fixed to the scale 5A and carryingthe sight windows 89A for displaying the range data 91A. Under thediaphragm 96A, the range carrier 91A is located rotatingly with respectto the diaphragm. In the FIG. 11 embodiment, the range carrier displaysthe numerical range data for 6 minutes, 60 minutes and 6 hours, togetherwith the corresponding range parts. The range carrier 91A is joined forrotation with a range switch handle 87A, which is in the form of acentrally located rotating knob 97 with a finger tip gripping depression98. In principle, the rotating knob 97 could be connected for rotationwith the diaphragm 96A in order to pivot the latter with respect to ascale plate 88A fixedly mounted on the instrument, but this wouldinvolve the disadvantage that the (terminal) range data 90A would nolonger be arranged angularly and rigidly with respect to the restposition 11A of the actuating element, whereby the interpretation of thetime indications, i.e., the legibility of the scale, would be somewhataffected.

The rotating knob 97 is mounted on a switch shaft 99, the latter held ina guide tube 100 extending centrally through the movement 95 and mountedrigidly on the instrument. The tube 100 is equipped at its lower endrigidly in rotation with the range switching contact spring 86A, becausein this embodiment, the printed circuit 27 with the switching contactson the bottom surface 101, is accessible to the contact spring 86A. Theguide tube 100 also serves to support the actuating element 1A along itsshaft end 54A, which here is in the form of a hollow shaft coaxiallysurrounding the guide tube 100.

In the embodiments according to FIGS. 10 and 12, it is possible in viewof the rotating support of the range scale plate 88, 88A that is notlimited angularly with respect to its sight window diaphragm 96, 96A torotate the range switch handle 87, 87A, without restriction, i.e., inany direction of rotation with respect to the rest position 11, from thelargest to the smallest range indication 90, 90A. However, as this isnot absolutely necessary and the shorter switching path over theintermediate range (in case of more than three ranges, over theintermediate ranges) is more practical in handling, it is sufficient torestrict the setting movement between the range carrier 91, 91A and thescale plate sight window 89, 89A angularly to the segment over which therange data 90, 90A on the range carrier 91, 91A extends. This results ina more stable configuration for the overall structure of the shortinterval timer 81, 81A as (in contrast to FIG. 10) it is not necessaryto install a freely rotating switching ring 92, or, as in the case ofFIG. 12, a freely rotating switching shaft 99A. Instead, the partsrigidly mounted on the instrument may be fixedly joined together aboveand underneath the rotatable range carrier 91, 91A by means ofcylindrical structural elements, wherein these cylindrical structuralelements are merely provided with segment-shaped passages, to permit thepassage of the moving connection between the range switch handle 87, 87Aand the range carrier 91, 91A which may be rotated over a limited angle(shown in FIG. 12 at the upper right-hand end of the guide tube 100).

A centered range switch handle 87 is simpler than a rotating center knob97, which switch handle being in the form of an axially actuable pushbutton 102 in the FIG. 13 embodiment. This push button 102 is arrangedin the center of a switching rib 4B for a range display 90B. For axialpressure actuation, this switch handle 87/102 may be smaller on theoperating side than is required for the uncomplicated handling of arotating knob 97 according to FIG. 11; while on the other hand, theconfiguration according to FIG. 13, in keeping with the conditionsaccording to FIG. 11, makes possible a scale 5 along the periphery ofthe short interval timer 81B and thus large arc segments between thescale sections.

In principle, it is possible to provide different axial position locksfor the push button 102 and to effect the switching of the range switch84 (FIG. 6) in this manner. This, however, would require an appreciableaddition layout effort in order to still be able to arrange the printedcircuit with the switching contacts on the outside of the movement 95,i.e., to avoid different conditions of intervention inside the movement95. Furthermore, clearly different axial locking positions would requirea substantial axial structural height of the short interval timer 81Boverall, and the obvious coordination of the time scale 5 with theprevailing range indication 90B would also be difficult.

It is more advantageous therefore, as shown in FIGS. 14, 15 to providein the case of an axially activated push button 102 for range switching,a displacement of the range carrier 91B parallel to the movement of theindicator rib 4 and, as in the embodiments according to FIGS. 9 to 13,combine this with a change in the range display 90B in the area of thescale 5B.

For this purpose, the push button 102 works against an axial returnspring 103 rigidly supported on the housing. An axially displaceableshaft 99, joined to the push button 102, is equipped on its mantlesurface with at least one axially extending and radially protrudingdeflecting rib 104. A front axial edge 105 of the rib 104 is inclinedwith respect to the axial direction. As seen in the representation inFIG. 15, projected onto the plane, the deflecting rib 104 and thus thepush button 102 are guided fixedly in rotation between supporting ribs106, mounted rigidly and in an axially parallel manner on theinstrument. In front of the frontal edge 105 of the deflecting rib 104is the correspondingly inclined frontal edge 107 of one of a pluralityof switching ribs 108 distributed over the circular circumference. Therib 108 is connected for rotation with the range carrier 91B and thuswith the switch contact spring 86B (FIG. 14). Upon the axial actuationof the push button 102 (FIG. 15) therefore, initially the range carrier91 is displaced axially, until its switching ribs 108 leave the slidingguide of the supporting ribs 106, at the bottom. As a result of theopposing force of the return spring 103 applied under and against therange carrier 91B, the frontal edge 107 slides along the frontal edge105 of the deflecting rib and the frontal edges 109 of the supportingribs, so that each switching rib 108 engages the next slide offset byone division of the supporting rib 106, while pushing back thedeflecting rib 104 (FIGS. 15c,15d). In this manner, the range carrier90B has been displaced by one range indication 90B. Obviously, theresetting of the range carrier 91 is not possible in this case; all ofthe range displays must be switched through by repeated axial pressureon the push button 102, in order to attain the initial position.

If it is to be avoided, that range switching may be performed during therun of the short interval timer 81B, i.e., prior to the rest position 11of the actuating element, the actuating element disk 3 may appropriatelybe equipped with a stop collar 111 and above it, the push button 102,with an axially parallel lock pin 112. A recess in the collar 111 islocated under the pin of the push button 102 only when the actuatingelement 1B has been moved back into its rest position. Only then can thedownwardly protruding free top end of the lock pin 112 penetrate theplane of the collar 111; only in the rest position 11 of the shortinterval timer 81B is range switching possible by actuating the pushbutton 102. However, fundamentally there would be no functionalinterference in case of a premature range switch, as from then on themotor 9 would be controlled with the latered pulse recurrence frequency,which then again corresponds to the instantaneous range display 90B withrespect to the prevailing position of the actuating element 1B on thescale 1, again the correct residual time period to the attainment of therest position is indicated. Depending on the practical conditions of theuse of such a short interval timer, irritation or even misunderstandingsmay occur, if at the start of the operation, following the setting ofthe actuating element 1B on the scale 5B with a range indication of 90B,at a later time the setting and the running time is altered, for exampleby another person, without this being recognizable.

In the case of conventional short interval household timers, thetransducer 19 is an acoustic signal emitter. Within the scope of theinvention, the latter naturally may be replaced in an adaptation todifferent conditions, for example, in an industrial application byanother transducer, such as an electro-optical signal emitter or even byan electromechanical or electronic control stage for the actuation ofdifferent processes.

Although the present invention has been described in connection withpreferred embodiments thereof, it will be appreciated by those skilledin the art that additions, modifications, substitutions, and deletionsmay be made without departing from the spirit and scope of theinvention, as defined in the appended claims.

What is claimed is:
 1. An electromechanical short interval timercomprising:a housing, an actuating element mounted on said housing formanual movement from a rest position, control means for returning saidelement to said rest position, and comprising:an electric motor,operably connected to said actuating element, an electric power source,an electric timekeeping circuit connected to said power source forsupplying electronic actuating pulses to said motor, and manuallyadjustable means for varying the pulse frequency supplied to said motor,and a signal emitter activated in response to said actuating elementreaching a predetermined position of its return movement.
 2. A timeraccording to claim 1, wherein said frequency varying means is operableto vary the pulse frequency to said motor by a factor of ten.
 3. A timeraccording to claim 1, wherein said frequency varying means is operableto vary the pulse frequency to said motor by a factor of six.
 4. A timeraccording to claim 1, wherein said frequency adjusting means comprises afrequency selector switch operably coupled to said timekeeping circuit.5. A timer according to claim 4, wherein said control means includes anoscillator circuit arranged to receive the variable pulses from saidtimekeeping circuit, said oscillator circuit being operably connected tosaid motor.
 6. A timer according to claim 4, wherein said control meanscomprises a printed circuit, said frequency selector switch comprising amovable contact spring engageable with said printed circuit.
 7. A timeraccording to claim 4, including a scale carrier on which is provided anindicia scale cooperable with said actuating element to indicate theselected time period, said frequency selector switch including a movablerange carrier having a manual actuator for moving said range carrierrelative to said scale.
 8. A timer according to claim 7, wherein saidrange carrier includes indicia corresponding to the variable pulsefrequencies.
 9. A timer according to claim 8, wherein said variablepulse frequency indicia is selectively visible through openings in saidhousing.
 10. A timer according to claim 4, wherein said actuatingelement comprises a first dial mounted for rotation, said pulsefrequency varying means comprising a frequency selector switch whichincludes a second dial mounted for rotation coaxially relative to saidfirst dial.
 11. A timer according to claim 10 including a push buttonmovable transversely relative to the planes of said first and seconddials, said push button including an inclined surface which isengageable with an inclined surface of said second dial to cam thelatter into incremental rotation each time said push button is pressedmanually.
 12. A timer according to claim 1, wherein said actuatingelement is arranged to activate a time-elapse circuit of said signalemitter before said actuating element returns fully to its restposition, said time elapse circuit being self-deactivating after apreset time elapse.
 13. A timer according to claim 12, wherein saidsignal emitter comprises an electroacoustic transducer.
 14. A timeraccording to claim 12 including a spring contact arranged to becontacted and deflected by said returning actuating element to activatesaid signal emitter.
 15. A timer according to claim 1, wherein saidactuating element is arranged to activate a timing circuit immediatelyprior to reaching said rest position for actuating said motor for apreset further duration.
 16. A timer according to claim 15 including aspring contact arranged to be contacted and deflected by said actuatingelement returning to its rest position.
 17. A timer according to claim15, wherein said timing circuit is also connected to said signal emitterfor operating the latter.
 18. A timer according to claim 17, whereinsaid timing circuit comprises a portion of said timekeeping circuit. 19.A timer according to claim 1, wherein said actuating element comprises arotary dial, a stop provided against which said actuating element abutsin both its rest position and its maximum rotated position, said stopbeing freely movable between first and second positions when engaged bysaid actuating element in its rest position and maximum rotatedposition, respectively, such that said actuating element rotates 360degrees from said maximum rotated position to said rest position.
 20. Atimer according to claim 19, wherein said stop comprises a rotatablymounted wedge-shaped member.
 21. A timer according to claim 20, whereinsaid actuating element comprises a boss extending into the path ofrotation of said wedge-shaped member.
 22. A timer according to claim 1including indicia means operably coupled to said frequency selectorswitch to be moved simultaneously therewith to display a time periodindicia corresponding to the selected pulse frequency.